1. Field of the Invention
The present invention relates to an engine control unit mounting apparatus for a motor vehicle and more particularly to an engine control unit mounting apparatus to be mounted in an engine compartment.
2. Prior Art
Generally, as shown in FIG. 6, an engine control unit 1 for controlling fuel injection, ignition timing and the like is disposed on the inner side of a front panel 2 of the passenger compartment or on the floor of the vehicle under a seat.
However, when the engine control unit is placed in the passenger compartment, long lead wires are necessary in order to connect the engine control unit with each of the various sensors, fuel injectors, the ignitor and other actuators.
Japanese Utility Model Application Laid-open No. Jitsu-Kai-Shou 56-5237 discloses a technique in which an engine control unit is installed in the engine compartment in order to solve these problems. A major problem when installing the engine control unit in the engine compartment is how best to protect the engine control unit from heat, electromagnetic fields and electrical noises.
In this prior art, the heat problem is solved by enclosing the engine control unit with a heat insulation box and, in addition, cooling the engine control unit with fuel passing through a fuel pipe provided in the heat insulation box.
However, since the heat insulation box is around the fuel pipe, the location of the engine control unit is restricted by the placement of the fuel pipe in the engine compartment.
Also, because the engine control unit is connected with various sensors and actuators, the engine has many lead wires and connecting terminals. In modern automobiles, these lead wires and terminals are integrated into a so-called wiring harness. There is an optimum design in arranging the wiring harness in the engine compartment, and this design restricts the location of the engine control unit as well.
Therefore, it is very difficult to find the best location for the engine control unit, which is close to the fuel pipe in the engine compartment while maintaining the best design of the wiring harness.
Further, the engine control unit is enclosed by the heat insulation box, and therefore the ground terminals for the inner electrical components must be extended outside the heat insulation box. This results in a complicated construction of the heat insulation box.